A novel method of composite electroplating on lap in lapping process

A lapping machine with the composite electroplating to dress the lap in-process has been developed. Mirror surface lapping operations on silicon wafers were conducted by plating tin with 0.3 μm Al2O3 particles on the lap surface in-process. During the lapping process, the cathode current density ranged from 0.28 to 1.68 A/dm2. Results showed that the removal rate of the silicon wafer for this process ranges from 0.12 to 0.18 μm/min, which is about 2.5–3.5 times higher than those without dressing in-process. This indicates that this novel method can produce sharp new edges on the lap surface continuously. It is found that the growth rate for the coating thickness of the lap is almost equal to its wear rate at the cathode current density of 0.28 A/dm2. Hence, it is not necessary to replace and dress during the lapping by using this method. The silicon wafer can be lapped to a surface roughness, Ra=2 nm in this novel method.